Why Does a Capacitor Block Steady DC After It Charges?

Why Does a Capacitor Block Steady DC After It Charges?

Foundational Physics Short Answer: A capacitor stops carrying steady direct current after it charges because its voltage builds up until it balances the battery voltage. In a simple battery–resistor–capacitor circuit, that leaves no voltage across the resistor to...
Why Do Real Batteries Have Internal Resistance?

Why Do Real Batteries Have Internal Resistance?

Foundational Physics Short Answer: Real batteries have internal resistance because moving charge through their materials and carrying out the chemical reactions that supply electrical energy are not perfectly lossless processes. When a battery delivers current, some...
Why Does Voltage Drop Across a Resistor?

Why Does Voltage Drop Across a Resistor?

Foundational Physics Short Answer: Voltage drops across a resistor because moving charge transfers electrical energy to the resistor and its surroundings. The charges keep flowing, but each coulomb has less electric potential energy after moving through the resistor...
Why Does Current Split at a Junction?

Why Does Current Split at a Junction?

Foundational Physics Short Answer: Electric current splits at a junction because charge has more than one path to follow. In a steady circuit, the total current entering the junction equals the total current leaving it. How much goes into each branch depends on the...